EP1597336B1 - Use of a selected legume starch in an industrial fluid - Google Patents

Description

The present invention relates to leguminous starches selected by their viscosity and solubility characteristics and an industrial fluid comprising one of these starches.

It also relates to a process for preparing leguminous starches thus selected.

It is particularly aimed at using leguminous starches thus prepared or selected as constituting a fluid intended for the wellbore field.

For the purposes of the present invention, the term "legume" means any plant belonging to the families Caesalpiniaceae, Mimosaceae or Papilionaceae and in particular any plant belonging to the family Papilionaceae, for example pea, bean or bean, the beetle, lentil, alfalfa, clover or lupine.

This definition includes in particular all the plants described in any of the tables contained in the R. HOOVER et al. entitled "Composition, Structure, functionality and Chemical modification of legume starches: a review" .

Preferably, the legume is selected from the group consisting of peas, beans, beans and fababeans.

• toutes les variétés sauvages de « pois lisse » (« smooth pea »), et
• toutes les variétés mutantes de « pois lisse » et de « pois ridé » (« wrinkled pea ») et ce, quelles que soient les utilisations auxquelles on destine généralement lesdites variétés (alimentation humaine, nutrition animale et/ou autres utilisations).

Advantageously, it is pea, the term "pea" being considered here in its broadest sense and including in particular:

• all wild varieties of "smooth pea"("smoothpea"), and
• all mutant varieties of "smooth pea" and "wrinkled pea", irrespective of the uses for which such varieties are generally intended (human nutrition, animal nutrition and / or other uses).

Said mutant varieties are in particular those designated "mutants r", "mutants rb", "mutants rug 3", "mutants rug 4", "mutants rug 5" and "mutants lam" as described in the article of CL HEDLEY et al. entitled "Developing novel pea starches" Proceedings of the Symposium of the Industrial Biochemistry and Biotechnology Group of the Biochemical Society, 1996, pp 77-87 .

According to another advantageous variant, the legume is a plant, for example a pea or faba bean variety, giving seeds containing at least 25% by weight (dry / dry) of starch.

"Legume starch" means any composition extracted, in any manner whatever, from a legume and in particular from a papilionaceous organism, and whose starch content is greater than 90%, preferably greater than 95%. %, these percentages being expressed by dry weight relative to the dry weight of said composition.

Advantageously, this starch content is at least 98% (dry / dry).

According to another variant, the protein content of said composition is less than 5%, preferably less than 2%, these percentages being expressed by dry weight relative to the dry weight of said composition.

Advantageously, this protein content is at most equal to 1% (dry / dry), preferably at most equal to 0.5%. It can, for example, be between 0.25 and 0.45%.

The composition that can be used as "leguminous starch" within the meaning of the present invention can also contain, generally at a total content of less than 5% (dry / dry), various other constituents than starch and proteins, in particular fats, colloidal substances, fibers, mineral elements, etc.

The amylose content of the starch contained in said composition can be in a wide range, ie between 3 and 80% and generally between 10 and 78%, these percentages being expressed by dry weight relative to the dry weight of starch content. in said composition.

According to a first variant, this amylose content is greater than 20% and less than 60%, especially between 22 and 55% (dry / dry).

In a particularly advantageous manner, this amylose content is greater than 32% and less than 53%, especially between 33 and 45% (dry / dry).

The starch contained in said composition may in particular have undergone at least one modification treatment chosen from the group comprising chemical treatments, physical treatments and enzymatic treatments.

The chemical treatments include in particular all known esterification, etherification, crosslinking or hydrolysis by acidic or oxidizing routes.

The physical treatments include in particular all known pre-baking, cooking, extruding, atomizing, or drying operations, those known as "Heat Moisture Treatment" or "Annealing", the treatment operations by microwaves or ultrasound, plastification or granulation.

The use of starches and starch derivatives derived from plants other than legumes, in particular from potatoes, maize or wheat, as constituents of industrial fluids is very widely described in the literature.

• se présentant généralement sous forme d'une solution, d'une dispersion ou d'une suspension aqueuse, d'une émulsion eau dans huile ou d'une émulsion huile dans eau, et
• présentant avantageusement une ou plusieurs des propriétés suivantes : viscosifiante, lubrifiante, de refroidissement, d'anticorrosion et/ou de protection temporaire.

By "industrial fluid" is meant here any non-food, non-pharmaceutical or non-cosmetological fluid, this fluid:

• which is generally in the form of an aqueous solution, dispersion or suspension, a water-in-oil emulsion or an oil-in-water emulsion, and
• advantageously having one or more of the following properties: viscosifying, lubricating, cooling, anticorrosion and / or temporary protection.

• fluides d'usinage comme décrit dans le brevet EP 649 460 au nom de la Demanderesse,
• bains de trempe des métaux comme décrit dans les brevets FR 2 530 668 et FR 2 671 103 au nom de la Demanderesse,
• compositions de protection temporaire d'objets, en particulier métalliques, comme décrit dans le brevet FR 2 508 051 au nom de la Demanderesse.

These may be, by way of examples, industrial fluids used as:

• machining fluids as described in the patent EP 649 460 in the name of the Applicant,
• quenching baths of metals as described in the patents FR 2,530,668 and FR 2,671,103 in the name of the Applicant,
• temporary protection compositions of objects, in particular metal, as described in the patent FR 2 508 051 in the name of the Claimant.

By "industrial fluid" is meant in particular any composition that can be used as well fluid ("Well Servicing Fluid") within the meaning of the patent FR 2,516,532 and US 4,392,964 .

This definition includes drilling fluids or drillings muds but also workover fluids, finishing fluids, sealing fluids, and so on. packer fluids "), well treating fluids, subterranean fluids, spacer fluids, hole abandonment fluids ).

Starches and derivatives derived from plants other than legumes are widely used in the preparation of well fluids, including drilling fluids or sludge, for more than 60 years.

Such use is exemplified, inter alia, in patents FR 1,244,623 , FR 2 206 375 , EP 0852 235 or CA 1077699 or more recently in patents US 6,133,203 , US 6,281,172 , EP 1 130 074 , US 6,391,830 , or US 6,180,571 .

To the knowledge of the Applicant, the only document truly exemplifying the use of a legume starch as a component of an industrial fluid, in this case a drilling mud, consists of the patent application. WO 02/12414 entitled "Drilling fluid comprising high-amylose starch".

In this document, it is recommended to physically modify, and especially by extrusion, the legume starch for use in drilling mud.

However, no detail is given or can be deduced on the extrusion conditions of said starch and therefore on the intrinsic characteristics, in particular of solubility and viscosity, of the resulting extruded starch, including at the level of the table located in page 9 of this document titled "Temperature Tolerance Extruded Legume Starch"

In this table are specifically measured the characteristics (including FANN viscosity) of application compositions of "drilling mud" type based on NaCl, clay and extruded starch (10 g / l), said characteristics being moreover measured at the temperature of only 150 ° C.

Similarly, it is not specified and it can not be deduced the intrinsic characteristics of the leguminous starch 32% amylose (called "Product") used in drilling muds ("Mud compositions I - IV") described on pages 7 and 8 of this application.

Furthermore, no precision is given as to the actual contents of starch, proteins, colloidal substances, fibers, lipids and other possible constituents of the products used in these examples.

In addition, the drilling muds exemplified herein are still tested under pH conditions that may be judged to be rather favorable.

Indeed, the pH of said drilling muds is always between 7.8 and 8.3 and therefore always has a pH value of less than 8.5, ie in a relatively low alkaline pH range compared to those most commonly considered in this application.

These conditions limit the possibilities of thermochemical destabilization of the starch during the preparation and then the use of the drilling mud and thus overvalue the effectiveness of said starch, in particular as a viscosifying additive and able to limit the loss of fluid ( "Fluid loss") of said sludge.

Moreover, the very swelling nature of the clays (attapulgite, bentonite) used in drilling muds ("Mud compositions I-IV") described on pages 7 and 8 of the application WO 02/12414 aforementioned is also able to limit the loss of fluid.
The articles Starch / Starke 41 (1989) pp 49-54 and Starch / Starke 39 (1987) pp 49-54 are publications on starch, more specifically on pea starches and in particular a detailed assessment of the physicochemical characteristics of these.

The Applicant has now found that it is possible, by appropriate selection of certain physico-chemical characteristics of leguminous starches, to advantageously improve the possibilities of using said starches as components of industrial fluids, in particular those which can be used under conditions high temperatures and / or high pH.

By "high temperatures" is meant here temperatures above 130 ° C, preferably above 135 ° C and in particular at least 140 ° C, to which are subjected to said industrial fluids during their uses.

"High pH" here means pH at least equal to 8.5, preferably between 8.5 and 12 and in particular between 9 and 11.5 in relation to the pH of said industrial fluids as prepared for their uses. .

The Applicant has in particular observed, after extensive research and analysis, that the selection of Brookfield viscosity characteristics and aqueous solubility of a legume starch, for example pea starch, advantageously improved the potential uses as a component of well fluids that can be used at both high temperatures and high pH.

The notions of "leguminous starch" and "industrial fluid" have been defined beforehand.

The "Brookfield viscosity" of the legume starch usable according to the invention is conventionally measured according to the instructions and equipment provided by BROOKFIELD ENGINEENING LABORATORIES, INC.

In the present case, this viscosity is measured at 20 ° C. on an aqueous 8% (dry) composition of said starch which has been stirred for 20 minutes at 1500 rpm.

• on détermine la teneur en eau exacte de l'amidon de légumineuse à tester, par exemple à l'aide d'une balance à humidité infra-rouge de type « SARTORIUS MA 30 »,
• on calcule alors la quantité d'eau nécessaire à rajouter à 40 g, exprimés en sec, dudit amidon aux fins d'obtenir une composition aqueuse dont la matière sèche est de 8 %,
• on introduit la quantité ainsi calculée d'eau (eau potable à 20°C) dans un bêcher en inox de 1 1,
• on met cette eau sous agitation (500 tours/min) à l'aide d'un agitateur de laboratoire, par exemple de type « TURBOTEST 33/300 S » muni d'une turbine défloculeuse d'un diamètre de 55 mm, livrée avec ce matériel,
• sous cette agitation, on introduit en quelques secondes les 40 g, exprimés en sec, d'amidon de légumineuse à tester,
• au moment où la totalité dudit amidon est introduit dans l'eau, on déclenche le chronomètre,
• on augmente la vitesse d'agitation à 1500 tours / min et on maintient cette agitation pendant 20 minutes,
• on détermine alors immédiatement la viscosité Brookfield de la composition aqueuse résultante, par exemple sur un dispositif « BROOKFIELD modèle RVF 100 » et en utilisant le mobile de l'appareil qui donne une lecture comprise entre 20 et 80 % de l'échelle du cadran de l'appareil,
• cette valeur est ici retenue comme la viscosité Brookfield (8 %, 20°C, 20 min, 1500 tours/min) de l'amidon de légumineuse testé.

This viscosity (hereinafter "Brookfield viscosity (8%, 20 ° C, 20 min, 1500 rpm")) may in particular be measured according to the protocol described below:

• the exact water content of the leguminous starch to be tested is determined, for example using a "SARTORIUS MA 30" infra-red moisture balance,
• the quantity of water necessary to add to 40 g, expressed in dry form, of the said starch is then calculated in order to obtain an aqueous composition whose dry matter is 8%,
• the quantity thus calculated of water (drinking water at 20 ° C.) is introduced into a stainless steel beaker of 1 liter,
• this water is stirred (500 revolutions / min) using a laboratory stirrer, for example of the type "TURBOTEST 33/300 S" equipped with a deflocculating turbine with a diameter of 55 mm, delivered with this material,
• under this stirring, the 40 g, expressed in dry form, of leguminous starch to be tested are introduced in a few seconds,
• at the moment when all of said starch is introduced into the water, the chronometer is started,
• the stirring speed is increased to 1500 rpm and this stirring is maintained for 20 minutes,
• the Brookfield viscosity of the resulting aqueous composition is then immediately determined, for example on a "BROOKFIELD model RVF 100" device and using the mobile of the apparatus which gives a reading of between 20 and 80% of the scale of the dial. the apparatus,
• this value is here chosen as the Brookfield viscosity (8%, 20 ° C., 20 min, 1500 rpm) of the leguminous starch tested.

The applicant company found, after much research and analysis, that leguminous starches thus selected were particularly suitable for use as components of industrial fluids under conditions of high temperatures and / or high pH and while remaining sufficiently stable and manipulable during operations conducted at room temperature (20 ° C).

• d'être utilisables, si on le souhaitait, à des températures au moins égales à 135°C, voire au moins égales à 141°C ou 144°C, températures susceptibles d'être atteintes aux fonds de puits lors de forages profonds,
• d'être utilisables, si on le souhaitait et y compris aux températures précitées, pour des gammes de pH élevés, par exemple des pH compris entre 8,5 et 12,
• d'être utilisables, si on le souhaitait et y compris aux températures et pH précités, dans des environnements très divers, par exemple en termes de salinité du milieu (dont eau salée ou saumure, saturée ou non, eau de mer, éventuellement reconstituée,...),
• de présenter, à température ambiante, de bonnes propriétés physiques, notamment de stabilité et de viscosité,
• de présenter, à température ambiante ou non, de bonnes propriétés applicatives, par exemple une bonne aptitude à la formation de gâteaux de filtration sur les parois des puits.

In the particular field of well fluids, the applicant company has notably observed that the implementation of such selected legume starches allowed said fluids:

• to be usable, if desired, at temperatures at least equal to 135 ° C, or even at least 141 ° C or 144 ° C, temperatures likely to be reached deep wells during deep drilling,
• to be usable, if desired and including at the aforementioned temperatures, for high pH ranges, for example pHs between 8.5 and 12,
• to be usable, if desired and including the above-mentioned temperatures and pH, in very different environments, for example in terms of the salinity of the medium (of which saline water or brine, saturated or not, seawater, optionally reconstituted, ...)
• to exhibit, at ambient temperature, good physical properties, in particular stability and viscosity,
• to present, at ambient temperature or not, good application properties, for example a good ability to form filtration cakes on the walls of the wells.

By "aqueous solubility" is meant here the percentage by weight of materials contained in said starch and which are soluble in distilled water at 20 ° C.

In the present case, a sample of the order of 5 g of leguminous starch is taken. The exact weight (called "P") of said sample is measured.

In a 250 ml beaker, 200 ml of distilled water are introduced with stirring at 20 ° C. and then the aforementioned amount P of legume starch. After stirring for 15 minutes, the resulting composition is centrifuged for 10 minutes at 4000 rpm and 20 ° C.

After centrifugation, 25 ml of supernatant liquid are taken and introduced into a glass crystallizer of diameter 95 mm, which has been dried and weighed beforehand.

The crystallizer is then placed in an aerated oven whose temperature is maintained at about 60 ° C. After evaporation of the water, the crystallizer is placed in an air circulation oven set at 103 ° C. ± 2 ° C. for 1 hour and then in a desiccator in order to cool the sample to room temperature.

The quantity called "M" of sample contained in the crystallizer is then weighed.

The aqueous solubility of the leguminous starch tested, expressed in%, is calculated according to the following formula: $$\mathrm{Aqueous\; solubility}\left(\%\right)=\frac{\mathrm{M\; x}200x100}{25\mathrm{x\; P}}$$

Among these leguminous starches selected according to the double criterion of viscosity and aqueous solubility, two families of products particularly suitable for use in accordance with the invention and in particular in the well fluids mentioned above have been found in particular.

• une viscosité Brookfield comprise entre 2 000 et 8 000 mPa.s, et
• une solubilité aqueuse comprise entre 15 et 50 %.

The first family (hereinafter referred to as "FAMILY 1") covers leguminous starches with:

• a Brookfield viscosity of between 2,000 and 8,000 mPa.s, and
• an aqueous solubility of between 15 and 50%.

• une viscosité Brookfield comprise entre 500 et 1 900 mPa.s, et
• une solubilité aqueuse comprise entre 30 et 80 %.

The second family (hereinafter referred to as "FAMILY 2") consists of legume starches that simultaneously:

• a Brookfield viscosity of between 500 and 1900 mPas, and
• an aqueous solubility of between 30 and 80%.

The Applicant company also considers that legume starches belonging to the two FAMILIES 1 and 2 thus selected constitute new industrial products.

• présenter des teneurs variables en amidon, amylose, protéines, matières grasses, fibres, substances colloïdales, éléments minéraux, et
• avoir subi au moins une modification par un traitement chimique ou physique.

In general, the leguminous starch that can be used as an industrial fluid component according to the invention may, in particular, as described in all of the foregoing:

• have variable contents of starch, amylose, proteins, fats, fibers, colloidal substances, mineral elements, and
• have undergone at least one modification by chemical or physical treatment.

As a result of this, the subject of the present invention is also a process for preparing a modified leguminous starch which can be used as constituent of an industrial fluid, characterized in that a leguminous starch is subjected to at least one treatment chemical or physical, such that the resulting legume starch conforms to any of the aforementioned Brookfield viscosity ranges and to any of the above-described water solubility ranges.

According to a first variant, a leguminous starch is subjected to a physical treatment, in particular of cooking or precooking, other than an extrusion treatment and in particular to a treatment on any device widely known to those skilled in the art. under the general term "drum dryer", including including single drum or double drum variants.

The Applicant Company has found that the drum drum treatments were particularly well suited to the effective preparation of two above-mentioned FAMILIES 1 and 2 of new industrial products selected according to the double criterion of viscosity and aqueous solubility.

These treatments have proved particularly suitable for the preparation of legume starches belonging to the aforementioned FAMILY 1.

The applicant company has also observed that the drum treatments allow, if desired, such an effective preparation by using, as raw materials, starches of native legumes ie having not previously undergone any chemical modification , physical or enzymatic.

This obviously does not exclude that these drum treatments can be performed on legume starches previously, simultaneously and / or subsequently modified in one way or another.

The drying drum treatment may for example be preceded by another treatment, in particular another physical treatment such as a passage on a nozzle or any other device for direct cooking by steam jet or indirect allowing instant cooking of a suspension of starch.

Moreover, the plaintiff company also observed that the extrusion treatments allowed such an effective preparation if, contrary to the teachings of the application WO 02/12414 it used leguminous starches which previously had been chemically modified, in particular weakly crosslinked, as raw materials.

• selon une variante, par le fait que l'on soumet un amidon de légumineuse, natif ou préalablement modifié, a un traitement autre qu'un traitement d'extrusion, en particulier un traitement sur un tambour sécheur,
• selon une autre variante, par le fait que l'on soumet un amidon de légumineuse chimiquement modifié, en particulier réticulé, à un traitement d'extrusion.

As a result, the process for preparing a modified legume starch according to the present invention can also be characterized:

• according to one variant, in that a native or previously modified leguminous starch is subjected to a treatment other than an extrusion treatment, in particular a treatment on a drying drum,
• according to another variant, in that a chemically modified, in particular crosslinked, leguminous starch is subjected to an extrusion treatment.

The merit of the Applicant is notably to have found that not only these two process variants were particularly well suited to the preparation of the two FAMILIES 1 and 2 mentioned above new starches of legumes selected according to the double criterion of viscosity and aqueous solubility, but also that said starches were particularly effective as components of industrial fluids having high pH, ie at least equal to 8.5, and / or exploitable at high temperatures, ie greater than 130 ° C.

In particular, said leguminous starches thus selected have proved to be remarkably effective components of well fluids, in particular drilling fluids, having pHs of between 9 and 11.5 while being exploitable at temperatures of at least 140.degree. ° C.

According to one variant of the present invention, at least one legume starch belonging to the aforementioned FAMILY 1 and at least one legume starch belonging to the above-mentioned FAMILY 2 is associated within a same well fluid.

It is quite surprising to note that said starches have not only at ambient temperature but also at high temperature, the physical characteristics necessarily required for their use as water-retaining agents in drilling muds, according to the standards in force. eg standards published by the American Petroleum Institute ("API").

• des amidons issus de pomme de terre, de maïs ou de maïs cireux (« waxy ») qui, pour être efficaces à température élevée, doivent obligatoirement être réticulés à un niveau très élevé, et
• des amidons de maïs riches en amylose qui ne présentent pas, à température ambiante, les caractéristiques physiques requises, notamment en termes de viscosité, de solubilité et de conformité au test API.

The starches of legumes thus selected according to the invention differ in particular:

• starches from potatoes, maize or waxy maize (waxy) which, in order to be effective at high temperature, must necessarily be cross-linked to a very high level, and
• corn starches rich in amylose which do not exhibit, at ambient temperature, the physical characteristics required, in particular in terms of viscosity, solubility and conformity to the API test.

• au moins un amidon de légumineuse utilisable conformément à l'invention, appartenant à l'une ou l'autre des FAMILLES 1 et 2 susmentionnées, et
• au moins un amidon non issu de légumineuse, de préférence un amidon de maïs et tout particulièrement un amidon de maïs présentant une teneur en amylose supérieure à 45 %, notamment comprise entre 46 et 75 %.

According to a variant of the present invention, it is however possible to associate, within the same industrial fluid, for example within the same well fluid:

• at least one leguminous starch which can be used in accordance with the invention, belonging to one or other of the aforementioned FAMILIES 1 and 2, and
• at least one non-leguminous starch, preferably a corn starch and more particularly a corn starch having an amylose content of greater than 45%, especially between 46 and 75%.

Said non-leguminous starch may advantageously have an amylose content of between 46 and 60% approximately. It may be native or have undergone at least one physical and / or chemical modification, such modification may have been made simultaneously or not to the possible modification that may have been suffered by legume starch used according to the present invention.

The invention will be better understood with the aid of the examples which follow and which show some advantageous modes of preparation of leguminous starches according to the invention and their uses in the general field of industrial fluids.

EVALUATION PROTOCOLS FOR THE FIELD OF AQUEOUS DRILLING FLUIDS

The following are the methods of evaluating starches, whether or not in accordance with the invention, as potential components of aqueous drilling fluids ("water-base drilling fluids"), in particular as retention agents ("filtrate reducing"). agents ").

This method consists in evaluating the physical properties of said starches in accordance with API 13 A (" API SPECIFICATION 13A - FIFTEENTH EDITION, MAY 1993 ") and more precisely according to" section 11 - STARCH "on pages 33-35 of that standard.

1) GENERAL PROTOCOL

• à base d'eau salée à 40 g/l de Nacl (« 40 g/l SALT WATER »), fluides dont on mesure la viscosité V à 600 t/min et on calcule le volume de filtration F selon les paragraphes 11.3 et 11.4 de ladite norme, et
• à base d'eau salée saturée (« SATURATED SALT WATER »), fluides dont on mesure la viscosité V' à 600 t/min et on calcule le volume de filtration F' selon les paragraphes 11.5 et 11.6 de ladite norme.

From a given starch, drilling fluids are prepared and evaluated respectively:

• based on salt water at 40 g / l of NaCl ("40 g / l SALT WATER"), fluids whose viscosity V is measured at 600 rpm and the filtration volume F is calculated according to paragraphs 11.3 and 11.4 of that standard, and
• based on saturated saline water ("SATURATED SALT WATER"), fluids whose viscosity V 'is measured at 600 rpm and the filtration volume F' is calculated according to paragraphs 11.5 and 11.6 of said standard.

The clay used for this evaluation is a low-swelling basic clay, conforming to the API standard ( «API STANDARD EVALUATION BASE CLAY "), in this case of the" HYMOD PRIMA "type from DOWELL - SCHLUMBERGER .

The values obtained from V, F, V 'and F' are then compared with the maximum values given in Table 11.1 "STARCH PHYSICAL REQUIREMENTS" on page 33 of this standard.

• V = 18
• V' = 20
• F = 10 cm³, et
• F' = 10 cm³

According to this table, the maximum values that can be attained for a product to be considered acceptable in the intended application are as follows:

• V = 18
• V '= 20
• F = 10 cm ³ , and
• F '= 10 cm ³

For the sake of simplicity, it is subsequently considered that a given starch has satisfactory physical characteristics since the set of values V, F, V 'and F' are at most equal to the aforementioned values (respectively 18, 20, 10 cm3 and 10 cm3).
By convention, such a starch is affublé the sign "+".

Conversely, it is considered that a starch does not have (completely) satisfactory physical characteristics since at least one of the values V, F, V 'and F' (a fortiori all the values V, F, V 'and F') is greater than the corresponding maximum value mentioned above.

By convention, such starch is affublé sign "-".

The above-described GENERAL PROTOCOL studies the behavior of a given starch without it having undergone, after its preparation, any particular post-heat or physical treatment.

As a result, the GENERAL PROTOCOL is here considered as being performed "at ambient temperature" or more precisely, at "low temperature / low pressure" and may be referred to below as "LTLPT" (for "Low Temperature / Low Pressure Test")

2) SPECIAL PROTOCOL

The applicant company has also studied the behavior of a certain number of starches according to the above-mentioned GENERAL PROTOCOL but after these starches have undergone, within a drilling fluid, a treatment which will be described below and which , by convention, will be designated "HTHPT" (for "High-Temperature / High-pressure Test").

• Eau déminéralisée 960,00 g
• Na Cl 25,60 g
• Mg Cl₂ 6H₂0 5,13 g
• Mg SO₄ 7H₂0 3,30 g
• K Cl 0,73 g
• Na H CO₃ 0,20 g
• Na Br 0,20 g
• Ca Cl₂2H₂O 1,45 g

In view of this "HTHPT" test, a "synthetic" seawater of the following composition is prepared:

• Demineralized water 960.00 g
• NaCl 25.60 g
• Mg Cl ₂ 6H ₂ O 5.13 g
• Mg SO ₄ 7H ₂ 0 3.30 g
• K Cl 0.73 g
• NaHCO ₃ 0.20 g
• Na Br 0.20 g
• CaCl ₂ 2H ₂ O 1.45 g

350 ml of the "synthetic" seawater thus prepared and 35 g of "HYMOD PRIMA" clay are then mixed for 30 minutes at 500 rpm.

The pH of this composition is then adjusted to a value of 10 with sodium hydroxide at 400 g / l.

350 ml of this composition are then mixed with 5 g of the starch to be tested for 20 minutes at 11,000 rpm in a "Hamilton Beach" type mixer.

The sludge obtained is poured into a stainless steel cell until it reaches a level located 1 cm below the upper edge of said cell.

The cell containing the sludge was pressurized with nitrogen (100 psi, about 6.9 bar or 690 kilo pascals) and placed in a roller oven for 16 hours at the desired temperature.

After cooling the cell to 20 ° C, its contents are poured into the HAMILTON bowl and mixed for 5 minutes at 11,000 rpm.

The values of V, F, V 'and F' are then determined directly according to the above-mentioned GENERAL PROTOCOL.

Then, as in the GENERAL PROTOCOL, the said values are compared with the above-mentioned maximum values (18, 20, 10 cm ³ and 10 cm ³ ).

For a temperature considered according to the test "HTHPT", each starch tested is affublé the sign "+" or the sign "-" according to the same conventions as those established previously, namely that the starch is considered satisfactory ("+" ) only if the set of values V, F, V 'and F' are at most equal to the above maximum values.

A starch which is affixed with the sign "-" at a certain temperature is not tested at any higher temperature.

EXAMPLE 1

In this example, a certain number of starches, whether or not conforming to the invention, are evaluated according to the above-mentioned GENERAL PROTOCOL.

• la nature de tout traitement chimique et/ou physique éventuel mis en oeuvre en vue de préparer ledit produit,
• la viscosité Brookfield (8 %, 20°C, 20 min, 1500 t/min) dudit produit telle que définie précédemment (ci après « VB »),
• la solubilité aqueuse dudit produit telle que définie précédemment (ci-après « SA »).

The following list includes, for each product, its name and characteristics, including:

• the nature of any chemical and / or physical treatment that may be used to prepare the said product,
• the Brookfield viscosity (8%, 20 ° C, 20 min, 1500 rpm) of said product as defined above (hereinafter "VB"),
• the aqueous solubility of said product as defined above (hereinafter "SA").

LIST OF TESTED STARCHES

• PEAS 1 = native pea starch (starch content> 98%, amylose content: about 38%, protein content: about 0.20%) - VB <5 mPa.s, SA = 0%.
• PEAS 2 = native pea starch (starch <98%, amylose: about 35%, proteins: about 0.50%) - VB <5 mPa.s, SA = 1.1%.
• PEAS 3 = native pea starch (starch> 98%, amylose: about 35%, proteins: about 0.35%) - VB <5 mPa.s, SA = 0%.
• PEAS 4 = PEAS 1 treated on drum dryer - VB = 4550 mPa.s; SA = 25.5%.
• PEAS 5 = Dried 1 sprayed drum - VB = 2300 mPa.s; SA = 16.2%.
• PEAS 6 = PEAS 1 treated on a nozzle and then on a drying drum - VB = 6450 mPa.s; SA = 43.5%.
• PEAS 7 = PEAS 1 treated on twin screw extruder - VB = 220 mPa.s; SA = 67.6%.
• PEAS 8 = POIS 2 treated on drum dryer - VB = 4300 mPa.s; SA = 19.7%.
• PEAS 9 = PEAS 2 treated on a nozzle and then a drying drum - VB = 7500 mPa.s; SA = 36%.
• PEAS 10 = PEA 3 treated on twin screw extruder - VB = 250 mPa.s; SA = 64.8%,
• PEAS 11 = POIS 3 treated on twin screw extruder - VB = 420 mPa.s; SA = 62.7%.
• PEAS 12 = PEAR 1 crosslinked with 0.1% by weight (dry / dry) of epichlorohydrin - VB <5 mPas; SA = 0%.
• PEAS 13 = PEAS 12 treated on twin screw extruder - VB = 95 mPa.s; SA = 31%.
• PEAS 14 = PEAR 1 cross-linked with 0.05% epichlorohydrin and then treated on a twin-screw extruder under the same conditions as PEAS 13 - BV = 1640 mPa.s, SA = 80%.
• STARCH A = potato starch treated on twin screw extruder - VB = 110 mPa.s; SA = 85%.
• STARCH B = potato starch cross-linked with 0.1% epichlorohydrin and then treated on a twin-screw extruder - VB = 880 mPa.s; SA 20%.
• STARCH C = corn starch cross-linked with 0.1% epichlorohydrin and then treated on a twin-screw extruder - VB = 54 mPa.s; SA = 4%.
• STARCH D = Amylose starch rich in amylose (EURYLON ^® 7) acetylated and then treated on a drying drum - VB = 1640 mPa.s; SA = 37%.

The table below indicates, for each starch tested, its Brookfield viscosity ("VB") and aqueous solubility ("SA") characteristics as well as its conformity (denoted "+") or its non-conformity (denoted "-" ) to all of the four conditions concerning the values of V, F, V 'and F' studied according to the GENERAL PROTOCOL, ie globally its conformity or not to the "LTLPT" test. PRODUCT VB (mPa.s) HER % TEST LTLPT POIS 1 <5 0 - POIS 2 <5 1.1 - POIS 3 <5 0 - POIS 4 4550 25.5 + PEAS 5 2300 16.2 + PEAS 6 6450 43.5 + POIS 7 220 67.6 + POIS 8 4300 19.7 + POIS 9 7500 36 + PEAS 10 250 64.8 + POIS 11 420 62.7 + POIS 12 <5 0 - POIS 13 95 31 - POIS 14 1640 80 + STARCH A 110 86 + STARCH B 880 20 + STARCH C 54 4 - STARCH D 1640 37 -

This table shows that among the pea starches studied here, only those prepared under conditions such that their Brookfield viscosity is at least about 100 mPa.s are likely to comply with the "LTLPT" test, ie to present the set of physical characteristics required for their use as retention agents according to API 13A above.

This excludes native products (POIS 1 to 3) but also, in particular, pea starches which, although chemically treated (POIS 12) or thermally (POIS 13), have a Brookfield viscosity of less than 100 mPa.s. The fact that the POIS 13 does not conform to the "LTLPT" test whereas the POIS 14 is in conformity with the said test, shows that the level of crosslinking agent used must be adapted, ie generally be limited, so that the product cross-linked and heat-treated extruder, can meet this requirement.

Moreover, the Applicant Company has observed that a pea starch having a Brookfield viscosity of greater than 20,000 mPa.s, whatever its mode of preparation, has a tendency to rapidly form a gel in aqueous solution and / or to be difficult to manipulable.

The table above also shows that an amylose starch starch such as STARCH D (amylose content: about 70%) does not meet the "LTLPT" test, although it has a Brookfield viscosity of 100 and 20,000 mPa.s.

Conversely, a potato starch such as STARCH A meets the "LTLPT" test, although having a Brookfield viscosity of less than 100 mPa.s.

The table above shows that the pea starches satisfying the "LTLPT" test can independently exhibit a wide variety of aqueous solubilities, especially between 10 and 85%.

This range excludes, in particular, native pea starches such as POIS 1, 2 and 3 (aqueous solubility equal to or close to zero), or very strongly modified, such as PEAS 12 and 13, which are considered unsatisfactory because of their low fixing power or water retainer.

EXAMPLE 2

In this example, a certain number of starches, which may or may not comply with the invention, are evaluated according to the above-mentioned specific protocol ("HTHPT" test).

The "HTHPT" test is first carried out at 130 ° C. and then at 135, 139, 141, 143 and 144 ° C., it being understood that a starch which does not satisfy the "HTHPT" test at a certain temperature (for example at 141 ° C. ° C) is, for this temperature, decked with the sign "-" according to the pre-established convention and is not tested at any higher temperature (eg at 143 or 144 ° C).

The table below indicates, for each starch tested and each temperature tested, whether said starch is compliant ("+") or non-compliant ("-") with the "HTHPT" test, ie verifies or not all four above-mentioned conditions concerning the values of V, F, V 'and F'. PRODUCT CONFORMITY OR NOT TO TEST HTLPT 130 ° C 135 ° C 139 ° C 141 ° C 143 ° C 144 ° C POIS 1 + + - - - - POIS 2 + + - - - - POIS 3 + + - - - - POIS 4 + + + + + - PEAS 5 + + + + + + PEAS 6 + + + + - - POIS 7 + + - - - - POIS 8 + + + + + + POIS 9 + + + + - - PEAS 10 + + - - - - POIS 11 + + - - - - POIS 12 + + - - - - POIS 13 + - - - - - POIS 14 + + + + - - STARCH A + - - - - - STARCH B + + - - - - STARCH C + + - - - - STARCH D + + - - - -

• des POIS 1 à 3, amidons de pois natifs qui ne vérifient pas le test « LTLPT » (cf. EXEMPLE 1).
• des POIS 12 et 13, amidons de pois réticulés avec 0,1 % d'épichlorhydrine qui ne vérifient pas simultanément le test « LTLPT » (cf. EXEMPLE 1) et le test « HTHPT » à 135 °C.
• de l'AMIDON A, fécule de pomme de terre extrudée qui n'est pas exploitable à 135°C selon le test « HTHPT ».
• Des AMIDONS C et D, amidons de maïs modifiés chimiquement et thermiquement qui ne vérifient pas le test « LTLPT » (cf. EXEMPLE 1).

This table shows that all the starches of legumes according to the invention, namely peas 4 to 11 and 14, not only verify the "LTLPT" test (see EXAMPLE 1) but also can be used at elevated temperature, ie at least 135 ° C according to the "HTHPT" test.
This is not the case :

• PEAS 1 to 3, native pea starches which do not check the "LTLPT" test (see EXAMPLE 1).
• PEAS 12 and 13, pea starches crosslinked with 0.1% epichlorohydrin which do not simultaneously check the "LTLPT" test (see EXAMPLE 1) and the "HTHPT" test at 135 ° C.
• STARCH A, extruded potato starch that is not usable at 135 ° C according to the "HTHPT" test.
• AMIDONS C and D, chemically and thermally modified corn starches which do not check the "LTLPT" test (see EXAMPLE 1).

All leguminous starches according to the invention are at least as efficient as starch B, potato starch crosslinked with 0.1% epichlorohydrin and heat treated for its preparation. This is particularly the case of POIS 7, 10 and 11 which however have not undergone any chemical modification, in particular of crosslinking, before being heat treated for their preparation.

• une viscosité Brookfield comprise entre 1 000 et 10 000 mPa.s, et
• une solubilité aqueuse comprise entre 12 et 80 %, sont encore plus performants puisqu'ils sont exploitables à 141°C, voire à 143 ou 144°C selon le test « HTHPT ».

It should be emphasized, however, that POIS 4, 5, 6, 8 and 9 (belonging to the aforementioned FAMILY 1) and POIS 14 (belonging to the aforementioned family 2), in accordance with the invention, which simultaneously exhibit:

• a Brookfield viscosity of between 1000 and 10,000 mPas, and
• an aqueous solubility of between 12 and 80%, are even more efficient since they are exploitable at 141 ° C, or even 143 or 144 ° C according to the test "HTHPT".

And it is remarkable to point out that such legume starches thus selected are able to be used effectively as components of drilling fluids without there being an urgent need to modify them chemically, in particular to crosslink them.

This is all the more surprising since the literature teaches, for starches in general, the need for extensive cross-linking (particularly by means of epichlorohydrin) to be truly exploitable at elevated temperatures.

Claims (10)

1. A legume starch which exhibits:

   - a Brookfield viscosity of between 2000 and 8 000 mPa.s.

   - a solubility in water of between 15 and 50%.
2. A legume starch which exhibits:

   - a Brookfield viscosity of between 500 and 1900 mPa.s.

   - a solubility in water of between 30 and 80%.
3. A process for preparing a legume starch according to claim 1 or 2 comprising the step of subjecting a native or previously modified legume starch to a drum dryer, or a chemically modified legume starch to an extrusion treatment.
4. An industrial fluid comprising a legume starch according to claim 1 or 2, wherein said industrial fluid is selected from the group of fluids for wells, machining fluids, baths for tempering metals and compositions for temporarily protecting objects, in particular metallic objects.
5. The industrial fluid as claimed in claim 4, wherein said industrial fluid exhibits a pH higher than 8.5.
6. The industrial fluid as claimed in claim 4 or 5, wherein said industrial fluid is intended to be used at a temperature higher than 130°C.
7. The industrial fluid as claimed in any one of claims 4 to 6, wherein said industrial fluid is a fluid for wells.
8. The industrial fluid as claimed in claim 7, wherein said fluid for wells exhibits a pH of between 8.5 and 12, preferably of between 9 and 11.5, and is intended to be used at a temperature higher than 135 °C, preferably higher than 140 °C.
9. The industrial fluid as claimed in claim 7, wherein said fluid is an aqueous drilling fluid.
10. Use of a legume starch according to claim 1 or 2 as a constituent of an industrial fluid according to any one of claims 4 to 9.